Plymouth Sound Research Articles

Species body size distribution patterns of marine benthic macrofauna assemblages from contrasting sediment types

Species body size spectra have been constructed for macrofauna assemblages from four sites with contrasting sediment granulometry and heterogeneity in and around Plymouth Sound. The number of species and species turnover (β diversity) were higher on coarse sediment. While the fauna were distinct between sites, the median geometric size-class was conservative (class 14; 0.153–0.305 mg dry blotted weight). Only one site had significantly lower heterogeneity within the species size spectrum, yet this was the most heterogeneous sediment. As such, we were unable to reject the null hypothesis that species body size distribution patterns are conservative despite differences in sediment granulometry and heterogeneity.

Benthic foraminiferal depth distribution within the sediment in a modern ria

The depth in sediment at which benthic Foraminifera are living is obviously of importance to high‐resolution stratigraphy. Sediment cores were retrieved in June 1994 and April 1995 from a range of sedimentological facies within Plymouth Sound. The cores were sub divided into sections and analysed for live (stained) benthic Foraminifera. Analysis revealed that maximum densities of live Foraminifera generally occurred within the uppermost 1 cm, particularly within muddy sediments. Sandy sediments exhibited a more diffuse distribution of live Foraminifera, although maximum densities occurred in the upper centimetres (1–3 cm) of sediment. An unusually deep distribution of the normally epifaunal species Elphidium crispum (Linné) was discovered in cores from Withyhedge Beacon both in 1994 and 1995. The live assemblages were subdivided into three groups on the basis of test type which broadly reflected the energy level of the environment.

Occurrence of the marine antifouling agent irgarol 1051 within the Plymouth Sound locality: Implications for the green macroalga Enteromorpha intestinalis

Water samples taken from the Plymouth Sound locality were analysed for the presence of the s-triazine herbicide Irgarol 1051, which is an ingredient of antifouling paints used on pleasure boats and ships. Irgarol 1051 was detected at all sampling sites within the Sound; the highest levels were found in close proximity to areas of high boat density, especially where water flow was restricted within marinas. Concentrations within the semi-enclosed Sutton Harbour were less than values predicted from leach rate data. The highest detected concentration of over 120 ng dm −3 significantly inhibited the growth of Enteromorpha intestinalis spores under laboratory conditions; the no effect concentration was 22 ng dm −3. Photosynthetic efficiency in the adult frond of E. intestinalis from Sutton Harbour marina was inhibited by Irgarol 1051 in the laboratory with an EC 50 (72 h) of 2.5 |Gmg dm −3. A small adverse impact on E. intestinalis reproduction within the harbour is therefore likely. More polluted sites identified elsewhere in Europe will suffer proportionally greater impact.

Ciliate growth rates from Plymouth Sound: comparison of direct and indirect estimates

Thein situgrowth rates of marine planktonic ciliates from Plymouth Sound were determined after fractionating the natural community into several size categories to remove predators of different sizes. Total communityin situgrowth rates varied from 0·01 to 0·57 d−1according to fractionation treatment, with the four most abundant taxa, comprising three species ofStrombidium, andMesodinium rubrum, achieving maximumin situgrowth rates of between 0·41 and 0·68 d−1. These values are approximately half the maximum theoretical rates calculated indirectly using an equation which relates ciliate growth to cell size and temperature. Given the conservative nature ofin situgrowth rate measurements, the growth rates reported here appear appropriate for a natural ciliate community growing within a nutritionally favourable environment.

A comparison of fixatives for the estimation of abundance and biovolume of marine planktonic ciliate populations

The effects of five treatments with four commonly used fixatives on the abundance and cell volume of marine planktonic ciliates were investigated on a natural community from Plymouth Sound. The fixative treatments were 5% and 9% Bouin's solution, 0.4% acid Lugol's iodine, 1% buffered formaldehyde and 1% glutaraldehyde. The abundance of the aloricate ciliate community varied according to fixative treatment, with Lugol's maintaining the greatest cell numbers, followed by Bouin's, glutaraldehyde and formaldehyde. The effects of the fixatives on the abundance of the two most common aloricate taxa, Balanion sp. and Strombidium epidemum were similar to, and components of, those for the aloricate population as a whole. However, there was little difference between the effects of different fixatives on the abundance of the tintinnid community, or on the abundance of the most common tintinnid, Tintinnopsis nana. Mean cell volumes of Balanion sp., S.epidemum and T.nana were greatest in samples fixed in formaldehyde, followed by glutaraldehyde, Lugol's and Bouin's. The mean population volume of the aloricate and tintinnid populations generally reflected this trend with greatest values recorded in formaldehyde- and glutaraldehyde-fixed samples, followed by Lugol's and Bouin's; however, the differential effects of the fixatives were not as great. Lugol's therefore appears to be the most effective fixative tested for the estimation of ciliate abundance and population volume, the latter being a function of abundance and cell volume.

Isolation and Molecular Characterization of Five Marine Cyanophages Propagated on Synechococcus sp. Strain WH7803

Five marine cyanophages propagated on Synechococcus sp. strain WH7803 were isolated from three different oceanographic provinces during the months of August and September 1992: coastal water from the Sargasso Sea, Bermuda; Woods Hole harbor, Woods Hole, Mass.; and coastal water from the English Channel, off Plymouth Sound, United Kingdom. The five cyanophage isolates were found to belong to two families, Myoviridae and Styloviridae, on the basis of their morphology observed in the transmission electron microscope. DNA purified from each of the cyanophage isolates was restricted with a selection of restriction endonucleases, and three distinguishably different patterns were observed. DNA isolated from Myoviridae isolates from Bermuda and the English Channel had highly related restriction patterns, as did DNA isolated from Styloviridae isolates from Bermuda and the English Channel. DNA isolated from the Myoviridae isolate from Woods Hole had a unique restriction pattern. The genome size for each of the Myoviridae isolates was ca. 80 to 85 kb, and it was ca. 90 to 100 kb for each of the Styloviridae isolates. Southern blotting analysis revealed that there was a limited degree of homology among all cyanophage DNAs probed, but clear differences were observed between cyanophage DNA from the Myoviridae and that from the Styloviridae isolates. Polypeptide analysis revealed a clear difference between Myoviridae and Styloviridae polypeptide profiles, although the major, presumably structural, protein in each case was ca. 53 to 54 kDa.

PHENOTYPIC CHANGES IN THE PROGENY OF NUCELLA LAPILLUS (GASTROPODA) TRANSPLANTED FROM AN EXPOSED SHORE TO SHELTERED INLETS

Nucella lapillus adults were transplanted from the exposed north Cornish coast (Bude) to two sheltered inlets in south Devon (Dart Estuary and Plymouth Sound), sites where the native populations had ceased breeding as a result of sterilisation by tributyltin (TBT) pollution. The transplants produced progeny, many of which survived to maturity and beyond (6 + years). The shell form of Bude individuals is typical of animals exposed to severe wave-action, i.e. of light construction with a large aperture to accommodate a broad foot allowing for strong adhesion. However, in contrast, the shell form of the progeny differed markedly from that of their parents; they had the characters associated with development under sheltered conditions and subject to severe crab predation, i.e. a robust structure and small aperture. Statistical analysis of the shell characters of the two generations indicated highly significant differences. It is concluded these observations provide evidence of the remarkable plasticity in the shell form of N lapillus in that both ‘exposed morph’ and ‘sheltered morph’ can be produced by the same gene pool when subject to the actions of the appropriate selection pressures.

Marine Pelagic Ciliates and Their Productivity During Summer in Plymouth Coastal Waters

The ciliate list for Plymouth waters has been extended by 14 species using modern taxonomic techniques. Ciliates were abundant in the plankton where they formed a significant food resource. Their community biomass and production was estimated to average 12 µ C 1 and 9 µ C 1 respectively during the summer. The ciliate community was dominated by a diverse assemblage of aloricate choreotrichs, suggesting a complex trophic role for this protozoan group.Ciliate protozoans are ubiquitous and often abundant in marine waters where they are frequently considered to play an important ecological role in trophic flux and nutrient cycling within the plankton (Fenchel, 1987). In spite of this, however, their ecological role in British coastal waters is poorly understood. In Plymouth waters, for instance, there has been only one previous study of marine pelagic Protozoa (Lackey & Lackey, 1963), despite the presence of a marine laboratory in the region for over 100 years. As the study by Lackey & Lackey (1963) focused solely upon the taxonomy of local protists, the ecological role of protozoans in Plymouth waters is unknown. To redress this anomaly the present pilot study was undertaken in Plymouth waters with the following objectives: to identify the dominant ciliates from this region using techniques unavailable to Lackey & Lackey (1963), to quantify ciliate abundance and cell sizes, and to estimate their biomass and production.Triplicate water samples were collected, using a 3-litre water bottle, from surface waters at each of four stations along a 20-km transect between Plymouth Sound (50°21'N 04°09'W) and the Eddystone Rock (50°ll'N 04°16'W) during June, July and August 1988.

Nitrogen metabolism in marine methanotrophs

Two new methane-oxidizing bacteria have been isolated from seawater samples from Plymouth Sound. These marine methanotrophs have an obligate requirement for NaCl and exhibit many properties of typical Type I methanotrophs previously isolated from freshwater environments. However, they are different from all other methanotrophs thus far described in that they failed to grow on all solid media tested. The nitrogen metabolism of both strains was investigated. They were not N2-fixers nor would they use ammonia as nitrogen source. They appeared to utilize the glutamate dehydrogenase pathway for the assimilation of ammonia under all growth conditions tested.

Shipwrecks of the Honourable East India Company around the world

Summary. Drawing upon extensive study of HEIC ships lost around the world, this contribution reviewed losses by sea area. Starting with UK shipwrecks and territorial waters, the survey included in the Thames Estuary the Albion, Hindostan, the loss of the Mars and Walpole near Margate; the Admiral Gardner and Britannia on the Goodwins (in the same convoy); Henry Addington, Earl of Abergavenny and Albemarle on the south coast, and four in the Isles of Scilly, finishing with strays in the Bristol Channel and Severn Estuary. An estimated 200–220 vessels were lost during the operation of the English East India Company. By comparison there were approximately 246 VOC ships wrecked around the world. Of these 27 sank in UK waters; six were lost on the Goodwin Sands (three part of the same convoy), and two in Plymouth Sound. A detailed paper is in preparation.

The use of the dog-whelk, Nucella lapillus, as an indicator of tributyltin (TBT) contamination

The term ‘imposex’ was coined by Smith (1971) to describe the superimposition of male characters onto unparasitized and parasitized females of gonochoristic gastropods. In Nassarius obsoletus (Say) the development of imposex results in the female having one or more of the following characters: (1) a penis with a duct leading to (2) a vas deferens which passes back to the ventral channel of the capsule gland and (3) convolution of the normally straight gonadial oviduct (Smith, 1980). Imposex in the similarly gonochoristic Nucella lapillus (L.) was first noted by Blaber (1970) who found females with penis-like outgrowths in Plymouth Sound populations. Subsequent studies (Bryan et al. 1986; Gibbs & Bryan, 1986) have demonstrated that the incidence and intensity of imposex have since increased markedly in the same populations and that the phenomenon is widespread around south-west England.

The Decline of the Gastropod Nucella Lapillus Around South-West England: Evidence for the Effect of Tributyltin from Antifouling Paints

A survey of the gastropod Nucella lapillus around the south-west peninsula of England has revealed that the incidence of ‘imposex’, the induction of male sex characters in the female, is widespread, that all populations are affected to some degree and that the phenomenon is most prevalent along the south (Channel) coast. Populations close to centres of boating and shipping activity show the highest degrees of imposex, especially those within the vicinities of the Helford, Fal, Salcombe and Dart estuaries and in Plymouth Sound and Tor Bay. Within Plymouth Sound the degree of imposex increased markedly between 1969 and 1985, coinciding with the introduction and increasing usage of antifouling paints containing tributyltin (TBT) compounds.

THE DESIGN OF A SLOTTED VERTICAL SCREEN BREAKWATER

This paper describes Che wave studies, model testing and structural design of a 250 metre long slotted vertical screen breakwater for a marina at Plymouth, England. The marina is being developed by Plymouth City Council to provide a purpose built facility for hosting the major long distance races that start or finish at Plymouth, in addition to the usual marina facilities for private boat owners. After examining three alternative locations Plymouth Council selected a site in the north-east corner of Plymouth Sound as shown in Figure 1. The site is confined on two sides by existing shipping channels and by a rocky shore on the land side. Exposure to wave attack is limited to the south west sector. Because the existing seabed at the marine site was the responsibility of the Duchy of Cornwall, an Act of Parliament was required before Plymouth Council could commence construction. The Act contains clauses regulating the use of the marina and the permissable changes to the wave conditions in the adjacent shipping channels.

Thermal infrared detection of submarine springs associated with the Plymouth Limestone

ABSTRACT Fresh groundwater within the Plymouth Limestone can be shown to be in hydraulic continuity with the marine waters of Plymouth Sound. Fresh groundwater discharges from the limestone in the form of submarine springs can be detected on the basis of temperature differences between the fresh groundwater and the marine waters, using an aircraft-mounted thermal infrared linescanner. Analysis of the thermal data is improved and aided by the use of the GEMS colour contouring analysis facility.

Groundwater Chemistry Change due to Tidal Fluctuations in the Stonehouse Brewery Well, Plymouth, England

The Stonehouse Brewery Well is sunk 24 m into the well‐cemented, fissure‐dominated Plymouth Limestone. Groundwater within the well can be shown to be in hydraulic continuity with the marine waters of Plymouth Sound. Groundwater was discharged from the well for 28 hours at approximately 13,500 L/h and samples taken hourly were subsequently analyzed for pH, conductivity, magnesium, potassium, sodium, chloride, calcium, and nitrate. The results of these analyses are reported and briefly discussed in particular the apparent tidally influenced cyclicity of certain data sets and the apparent influence of the upcoming of saline water beneath the pumped well upon the chemistry of the discharged well water.

Notes On molluscan meiofauna from Plymouth

Preliminary examination of marine meiofauna from the Plymouth area, especially on mesopsammic representatives, resulted in the finding of several typically interstitial Mollusca. Among them, Caecum glabrum, Hedylopsis spiculifera, and Philinoglossa praelongata were recorded live for the first time in the area. This is also the first record of Ph. praelongata outside the Mediterranean Sea.During a short stay at the Marine Biological Association Laboratory some preliminary studies on meiofauna were made. To obtain information especially about the interstitial fauna of marine sand, three typical samples of coarse sediment from different positions were examined.Sample A: Plymouth Sound, Outer Cawsand Bay, Queens Ground, 50°20' 03“ N, 4° 10' 27” W; ca. 6 fathoms (=11 m); coarse sand, about 6 1 examined (14 September 1982).Sample B: Plymouth Sound, southwest of Drake Island, 50° 21' 06“ N, 4° 09' 50” W; ca. 7 fathoms (= 13 m); coarse shell-sand, about 1 1 examined (15 September 1982).Sample C: outer Plymouth Sound, 50° 18' 51“ N, 4° 10' 30” W; ca. 12 fathoms (– 22 m); fine gravel, about 1 1 examined (15 September 1982).In this contribution only the gastropods are dealt with; other meiofauna will be treated ina later communication. The sole previous report of mesopsammic fauna from the Plymouth area is that of Spooner (1959). He examined two samples, one of which (Plymouth Sound) was taken fairlyclose to the above sample A, about 18“ more to the West at 4–5–5–5 fathoms (8–10 m; G. R. Forster, personal communication).

Reproductive and nutritional periodicities in the starfish,Marthasterias glacialis, from Plymouth Sound

The gonadial, pyloric caecal and somatic cycles over three consecutive years in a subtidal population of the starfishMarthasterias glacialisfrom Plymouth Sound are described. The study area lies towards the eastern limit of the up-Channel range of this species, and this is reflected in only partial reciprocity between gonadial and pyloric indices, and also by the apparent utilisation of somatic material during the build-up of gametes. The sequence of events at the cytological level during gonadial build-up is described.

Responses of a hydroid to surface water samples from the River Tamar and Plymouth Sound in relation to metal concentrations

The River Tamar and its tributaries drain a highly metalliferous area; and increased metal levels in river water might be expected to affect biological water quality in the estuary. In order to detect possible effects we have used sensitive responses to stress of the hydroid Campanularia flexuosa as an index of quality of water samples from the River Tamar, Plymouth Sound and Cattewater. No water samples caused inhibition of colonial growth rate, but in each experiment there were significant variations in other more sensitive responses. It is these variations that we have related to metal distributions, although of the metals measured, only copper and cadmium occasionally occur in concentrations that could be biologically significant, and at the same time show any correlation with the hydroid responses. The limitation of the survey to water of relatively high salinity does not permit a firm conclusion about the origin of these metals, but there are some indications that local inputs may be important.

The distribution of mercury in the sediments of the plym estuary

Surface sediment samples collected in the Plym Estuary have been analysed for Fe, Mn, Hg, clay content and organic carbon. Statistical analysis of the data showed that Fe, Mn, clay and organic carbon concentrations all correlate well with each other. The Hg concentrations, which were in the range 18–2610 ng/g, had no strong correlations with any other sedimentary variable. A cluster analysis of the samples revealed the existence of three geochemical facies. Cluster facies P was located upstream and had sediments that were poorly sorted with Hg concentrations above those normally found in the rocks and soils of the catchment area. Cluster facies Q, further downstream, consisted of increased levels of Fe, Mn, clay and organic matter which suggested that estuarine precipitation processes were an important factor. The Hg concentration only increased by 16% and the results indicated a possible loss of Hg to Plymouth Sound. Cluster facies R consisted of sediments that were polluted. The analyses are discussed in terms of the sources and sinks of Hg within the estuary.

On the nutrition and metabolism of zooplankton XIII. Further studies of steroids inCalanus

The presence inCalanus finmarchicusof the sex hormone oestradiol-17β has been confirmed by gas chromatography-mass spectrometry (GC-MS) using the trimethylsilyl and heptafluorobutyrate derivatives.Levels of the sex hormone testosterone have been measured by radioimmunoassay inCalanus helgolandicuscollected from Plymouth Sound, and inC. finmarchicuscaptured off the Norwegian coast. Concentrations inC. helgolandicusvaried during the year from 150 to 626 fg/animal, accounting for 2.3 to 437 x 10-7% of the lipid content and 10.8 to 64.8 x 10-6%percnt; of the total sterol fraction. The mean level in Stage V C.finmarchicus,captured during spring, was 196 fg/animal.Testosterone was identified in C.finmarchicusby GC-MS of thetert-butyldimethylsilyl derivative.